Gervais Lake
Gervais Lake in Ramsey County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 5 ft visibility. Phosphorus: 39 µg/L. Chlorophyll-a (algae): 15.5 µg/L. Maximum depth: 41 ft. Surface area: 235.01 acres.
- Clarity
- 5 ft
- Typical in August
- 61°F
- Max depth
- 41 ft
- Area
- 235 acres
- Type
- Eutrophic
- Trend
- ↓ Declining
- Public access
- No
- Ice-out
- Apr 3
- Open water
- 245 days
Grade D measures nutrients and algae, not whether this is a good place for a cabin trip. Cabins and rentals near Gervais Lake →
Next lake in Ramsey County
Gervais Lake is a 235-acre productive, nutrient-rich eutrophic lake in Ramsey County, Minnesota with a maximum depth of 41 feet. Water quality is graded D based on 2 sampling years through 2025. Overall water quality is declining over recent sampling years. The lake supports 14 documented fish species including black bullhead, black crappie, and bluegill. No public access — the lake is private or restricted. Compared to the 43 other monitored lakes in Ramsey County, Gervais Lake ranks #34 for water quality.
Source: EPA Water Quality Portal sampling records, Minnesota DNR LakeFinder, last sampled 2025-09-23. Grade methodology: LakeGrade methodology.
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Swimming Safety
Grade onlyBacteria B
Based on clarity and algae grades from past sampling — we do not hold live water temperature and a current cyanobacteria reading for this lake. Check your state or county health department before you swim.
Based on E. coli testing, Gervais Lake rarely exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 1.1% of 92 samples across 3 seasons.
This is a historical summary of past testing, not a current condition — bacteria levels change quickly, especially after rain. Always check Minnesota’s current beach and health-department advisories before swimming.
Water Quality Grade: D (Nutrient-rich)
Murky, only visible to about 5 ft. Phosphorus level: 39 µg/L. Chlorophyll-a: 15.5 µg/L. Trophic State Index: 56.
| Metric | Value | Grade |
|---|---|---|
| Water Clarity (Secchi Depth) | 5 ft | Not graded |
| Phosphorus | 39 µg/L | Fair |
| Chlorophyll-a (Algae) | 15.5 µg/L | Poor |
| Trophic State Index (TSI) | 56 | Eutrophic |
High nutrients, frequent algae, reduced clarity
Where to stay near Gervais Lake
Compare lakeside cabins, hotels, and vacation rentals near Gervais Lake in Ramsey County, Minnesota — live availability and prices for your trip. Switch the map to Satellite to see the lake and how close each stay is to the water. The water-quality grade measures nutrients and algae, not lodging — cabins and rentals around Gervais Lake are listed below.
Top-rated places to stay near Gervais Lake
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Planning a whole trip? See where to stay at Minnesota’s top lakes →
Water Temperature
Gervais Lake typically sits around 61°F at the surface in August. Summer average is about 59°F. Usually warmest in Aug (about 61°F) and coldest in Jan (about 37°F). These are typical values by month — not a live reading.
Typical surface water temperature by month, from 1,332 field readings (2010–2025) via the EPA Water Quality Portal. See the full Gervais Lake water temperature breakdown →
Lake Details
| Characteristic | Value |
|---|---|
| Maximum Depth | 41 ft |
| Surface Area | 235 acres |
| Shoreline Length | 3.3 mi |
| Littoral Zone | 39% |
| Public Access | No |
Lake Size & Watershed
Size, shoreline, and watershed area from HydroLAKES (HydroSHEDS).
Fish Species
Click a species to see every graded lake where it is documented.
Fishing Gervais Lake
Invasive & Introduced Species
Red chips are ecologically harmful invasive species. Gray chips are stocked or introduced fish that aren't a current ecological concern.
DNR Fisheries Survey Summary
12 surveys on file from MN DNR Fisheries. Most recent: 2021-09-07 (Targeted Survey).
Top Species by Catch Rate
| Species | Avg CPUE | Avg Weight |
|---|---|---|
| Bluegill | 62.00 | 0.14 lb |
| Green Sunfish | 9.61 | 0.06 lb |
| Black Crappie | 9.59 | 0.18 lb |
| Spottail Shiner | 8.71 | — |
| Yellow Perch | 7.41 | 0.13 lb |
| Largemouth Bass | 7.27 | 0.9 lb |
CPUE = catch per unit effort, averaged across surveys (excludes juvenile shoreline seining). Higher CPUE = more abundant in standardized sampling.
Length Distributions
Number of fish caught at each inch class in the most recent survey that recorded lengths. Red dashed line marks an approximate trophy threshold for that species.
Bluegill
Green Sunfish
Black Crappie
Yellow Perch
From the 2021-09-07 survey
A targeted survey of nearshore and littoral fish species in Gervais Lake was conducted beginning on September 7th, 2021 by Index of Biological Integrity (IBI) Program Staff. Sampling sites were evenly spaced around the lake and each was sampled by backpack electrofishing and seining with a 50-foot or 15-foot seine,…
DNR Reports & Resources
Minnesota DNR LakeFinder publishes lake survey, fish stocking, water access, and aquatic plant data for Gervais Lake. 2 reports on file.
These links open on the official state DNR websites (Wisconsin DNR survey PDFs · Minnesota DNR LakeFinder).
- —Fisheries Lake Survey — GervaisFisheries Lake Survey · MN DNR LakeFinder
- —Fish Stocking History — GervaisFish Stocking History · MN DNR LakeFinder
Water Quality Trend: ↓ Declining
Based on 6 years of monitoring data (2020-2025).
| Metric | Trend | Change/Year | Years |
|---|---|---|---|
| Water Clarity | ↓ Declining | -0.113 m/yr | 6 |
| Phosphorus | ↑ Improving | -1.41 µg/L/yr | 6 |
| Chlorophyll-a | ↓ Declining | +2.19 µg/L/yr | 6 |
Ice Season
Historical ice data from Minnesota DNR (60 observations).
Estimated open water season: 245 days
| Earliest | Latest | |
|---|---|---|
| Ice-Out | 2024-03-07 (2024) | 2018-04-30 (2018) |
| Ice-In | 2014-11-15 (2014) | 2001-12-20 (2001) |
Most recent ice-out: 2026-03-29
EPA Impairment Status
Gervais Lake is officially listed as impaired under Clean Water Act §303(d) in the 2024 EPA reporting cycle (IR category 5).
Causes of impairment
A Total Maximum Daily Load (TMDL) plan has been approved.
Source: EPA ATTAINS assessment unit MN62-0007-00 · Official waterbody report
County Ranking
Ranked #34 of 44 lakes in Ramsey County
Nearby Lakes With Higher Grades
Gervais Lake holds Grade D. 3 nearby lakes hold higher nutrient-and-algae grades — useful for a swim day, not a reason to skip lodging here.
See full comparison →Nearby Lakes in Ramsey County
Frequently asked questions about Gervais Lake
What is the water quality grade for Gervais Lake?
- Gervais Lake in Ramsey County, Minnesota has a water quality grade of D (Nutrient-rich). Water clarity: 5 ft visibility. Phosphorus: 39 µg/L. Chlorophyll-a (algae): 15.5 µg/L. Maximum depth: 41 ft. Surface area: 235.01 acres.
Is Gervais Lake safe to swim in?
- Based on E. coli testing, Gervais Lake rarely exceeded the EPA safe-swimming threshold (235 MPN/100mL) — on 1.1% of 92 samples across 3 seasons. That works out to a bacteria swim-safety grade of B — a historical summary of past testing, not a current reading. Gervais Lake has a water quality grade of D (Nutrient-rich). Bacteria levels can spike quickly after heavy rain, so always check Minnesota's current beach and health-department advisories before you swim.
What is the water temperature of Gervais Lake?
- Gervais Lake typically sits around 61°F at the surface in August, from 1,332 EPA Water Quality Portal field readings (2010–2025). That is a typical value for the month, not a live reading.
How deep is Gervais Lake?
- Gervais Lake has a maximum depth of 41 feet. The lake covers 235.01 acres.
What fish are in Gervais Lake?
- Fish species found in Gervais Lake include black bullhead, black crappie, bluegill, common carp, green sunfish, hybrid sunfish, largemouth bass, northern pike, pumpkinseed, tiger muskellunge, walleye, white sucker, yellow bullhead, yellow perch. Gervais Lake is located in Ramsey County, Minnesota.
When does Gervais Lake thaw?
- Gervais Lake typically has ice-out around Apr 3. Ice typically forms around Dec 4. The open water season is approximately 245 days.
Explore Gervais Lake across LakeGrade
Depth, room, public access, and the state wake-sport rules
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Fish species and best lakes in Ramsey County
Species activity outlook by water temperature and season
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High nutrients, frequent algae, reduced clarity
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Where this data comes from
734 measurements from 1 monitoring station, 2020–2025. Retrieved from the EPA Water Quality Portal on 2026-08-02.
Collected and reported by
- Minnesota Pollution Control Agency - Ambient Surface Water
MNPCA734 samples · 2020–2025
Analytical methods
- Field measurement/observation, generic method
- Phosphorus by Colorimetry
- Phosphorus by Two Reagent Colorimetry
- 10200 H ~ Chlorophyll a-b-c Determination
- 2130 B ~ Nephelometric Method
- Turbidity, Nephelometric Method
- Turbidity by Nephelometry
Monitoring station identifiers (1)
Grade thresholds from the EPA National Lakes Assessment (EPA 841-R-24-006, Table 6-3), applied by ecoregion. See how grades are calculated and data sources.
Other records on this page
Impairment status from EPA ATTAINS 303(d) database
Lake size & watershed from HydroLAKES (HydroSHEDS)
Lake details from Minnesota DNR LakeFinder
Ice data from Minnesota DNR Climate